Table-Level Locking Hints in SQL Server

I was recently asked by a friend, how can we control the level of locking in SQL Server when executing SELECT, UPDATE, INSERT and DELETE statements.

The answer to this question is by using locking hints. Locking hints direct SQL Server to the type of locks to be used. Even though the SQL Server Query Optimizer automatically determines the best locking option when executing a statement of the above kinds, there are cases where a DBA/Database Developer might needs to explicitly control the level of locking.

 

Available Locking Hints in SQL Server

The available locking hints in SQL Server are the following:

HOLDLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

NOLOCK
Applies to: SELECT

PAGLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

READCOMMITTED
Applies to: SELECT, UPDATE, INSERT, DELETE

READPAST
Applies to: SELECT, UPDATE, DELETE

READUNCOMMITTED
Applies to: SELECT

REPEATABLEREAD
Applies to: SELECT, UPDATE, INSERT, DELETE

ROWLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

SERIALIZABLE
Applies to: SELECT, UPDATE, INSERT, DELETE

TABLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

TABLOCKX
Applies to: SELECT, UPDATE, INSERT, DELETE

UPDLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

XLOCK
Applies to: SELECT, UPDATE, INSERT, DELETE

The syntax for using locking hints is very simple. You only have to add the expression with (LOCKING_HINT) just right after you are referencing a database table name (or after a table alias) in your query.

Example of Using Locking Hints in SQL Server

An example of using the NOLOCK locking hint within a SELECT statement is the following:

SELECT column
FROM table with (NOLOCK)

The following MSDN Library link fully describes the above locking hints.

 

Learn More Tips like this – Enroll to the Course!

Check our online course on Udemy titled “Essential SQL Server Administration Tips(special limited-time discount included in link).

Via the course, you will learn essential hands-on SQL Server Administration tips on SQL Server maintenance, security, performance, integration, error handling and more. Many live demonstrations and downloadable resources included!

Essential SQL Server Administration Tips - Online Course with Live Demonstrations and Hands-on Guides
(Lifetime Access/ Live Demos / Downloadable Resources and more!)

Learn More

 

Upgrade your Tech Skills – Learn all about Azure SQL Database

Enroll to our online course on Udemy titled “Introduction to Azure SQL Database for Beginners” and get lifetime access to high-quality lessons and hands-on guides about all aspects of Azure SQL Database.

Introduction to Azure SQL Database (Online Course - Lifetime Access)
(Lifetime Access/ Live Demos / Downloadable Resources and more!)
Learn More

 

 

Featured Online Courses:

 

Read Also:

 

Subscribe to our newsletter and stay up to date!

Subscribe to our YouTube channel (SQLNetHubTV)!

Like our Facebook Page!

Check our SQL Server Administration articles.

Check out our latest software releases!

Check our eBooks!

 

Rate this article: 1 Star2 Stars3 Stars4 Stars5 Stars (No Ratings Yet)

Loading...

Reference: SQLNetHub.com (https://www.sqlnethub.com)

© SQLNetHub